This invention relates generally to industrial freezers and more particularly to a novel construction of the walls of industrial freezers used in manufacturing frozen dairy products such as ice cream bars.
Typically, industrial freezers of the type with which the invention is concerned are constructed as rectangular boxes, the walls of which have inner and outer stainless steel metal panels or skins separated by metal structural members and insulation. The skins and metal structural members are usually fastened together by way of metal fasteners and/or welding techniques.
Recent outbreaks of bacteria caused illnesses have motivated the dairy/ice cream industry to reexamine the design of freezers with an eye toward minimizing the potential for bacterial growth and eliminating such bacterial growth should it occur through frequent heat sterilization of the freezer components. Prior freezers were confronted with two problems. First, it was discovered that there was a propensity of bacteria to multiply and grow in the vicinity of joints, fasteners and other surface discontinuities. Second, the freezer components, particularly the wall structures, were subjected to increased thermal stress caused by cycling the freezer between its normal processing temperature of about -50.degree. F. and the necessary sterilization temperature of about 170.degree. F. Thus, it became readily apparent that prior conventional freezers could not maintain their structural integrity under the increased thermal stress conditions created by frequent sterilization necessary to avoid bacterial growth.